ASR/BNG shared-policy-instance and QoS Policy

[administrator]

Hi,

We have ASR 9006 and use RADIUS to create unique shared-policy-instance for each of our subscribers.

Radius Access-Accept message include,

sub-qos-policy-in=GOLD_SERVICE shared-policy-instance spi_{uniqueID}_in

where GOLD_SERVICE is the policy-map.

Now I want to change subscriber's policy-map without taking down BNG session.

I know modifying SPI with CoA is not supported, but we can do it with XML API or CLI or SNMP or anything?

[xthuijs]

I haven't tested it, but I was thinking something like:

define a service that contains the policy-map.

apply the service to the session either via access-accept or dynamic template or COA.

to modify the QOS simply unapply the service via COA and reapply a new service that holds a different QOS policy?

would that meet your need?

xander

[xthuijs]

oh scratch that idea... it would work, but it omits the shared policy concept that you're after too.

let me think about this more, I'll be back if I have news!

xander

[xthuijs]

got some news!

so with SPI we can't modify the actual definition of the policy while it is active (that is via "pQOS"), so we can't modify the classes, insert/delete or modify them, BUT we can do the following.

How about we move 2 sessions that "belong together" to move to a new SPI instance on a new predefined policy.

For instance, you have GOLD applied with SPI name "X", tied to 2 sessions. Then, we can modify session 1 first to SILVER and SPI "Y" and next coa request is moving session "2" to SILVER and SPI "Y".

would that model work for you?

only "gotcha" is here that GOLD and SILVER need to be predefined policies in the XR configuration.

cheers!

xander

[administrator]

Hi Xander,

Thank you for your response.

I though it is a great idea, so I tried your suggestion, but CoA doesn't seem to work. I create spi and attached two sessions on this.

Then, try to issued CoA to change sub_qos_policy on one of the session with new spi, but gets CoA NACK with error-cause "Administratively Prohibited."

Existing session

UpstreamQoSPolicy IN_10M shared-policy-instance spi_031716_10M_in

DownstreamQoSPolicy OUT_25M shared-policy-instance spi_031716_25M_out

CoA Message

attribute1=44,0000016d
attribute2=26,9,1,"sub-qos-policy-in=IN_1M   shared-policy-instance spi_031716_1M_in"
attribute3=26,9,1,"sub-qos-policy-out=OUT_1M shared-policy-instance spi_031716_1M_out"

Last COA response: Result NACK
COA Response  Attribute List: 0x10010f70
1:  error-cause     len=  4  value= Administratively Prohibited
2:  reply-message   len=  9  value= CoA error

[xthuijs]

aha yeah that what you have you can't do: because the SPI instance can't be the same on in and out.

SPI will link queueID's together, or actually use the same set of qid's for those shaped classes.

on ingress it is not advice-able to have shaping on bng subs (due to limit ingress queue scale).

cheers

xander